Design and fabrication of an angular microactuator for magnetic disk drives

Abstract

Angular electrostatic microactuators suitable for use in a two-stage servo system for magnetic disk drives have been fabricated from molded chemical-vapor-deposited (CVD) polysilicon using the HexSil process. A 2.6-mm-diameter device has been shown to be capable of positioning the read/write elements of a 30% picoslider over a 6 6 61m range, with a predicted bandwidth of 2 kHz. The structures are formed by depositing polysilicon via CVD into deep trenches etched into a silicon mold wafer. Upon release, the actuators are assembled onto a target wafer using a solder bond. The solder-bonding process will provide easy integration of mechanical structures with integrated circuits, allowing separate optimization of the circuit and structure fabrication processes. An advantage of HexSil is that once the mold wafer has undergone the initial plasma etching, it may be reused for subsequent polysilicon depositions, amortizing the cost of the deep-trench etching over many structural runs and thereby significantly reducing the cost of finished actuators. Furthermore, 100-m-high structures may be made from a 3-m deposition of polysilicon, increasing overall fabrication speed. [256]

Micromachined High-Aspect-Ratio Parylene Spring and Its Application to Low-Frequency Accelerometers

“…Futhermore, the mass is much larger than that of previous MEMS accelerometers. As a result, as given by (1) is as low as 25 or , which is three orders of magnitude smaller than the noise floor measured.…”

“…HEXSIL [24], [25] and HARPSS [26] have also been proposed for high-aspect structures, where deep trenches are refilled with poly-Si. However, both single crystal Si and poly-Si are brittle, so mechanical failure is of considerable concern.…”

Contrôle actif de structures micro-électromécaniques

“…Angular actuation is widely selected (e.g. against linear actuation), because such a configuration allows high lateral stiffness, minimizing the sensitivity of the MEMS-based servo-system to shock loading in the plane of the disk [4]. In addition, electrostatic actuation appears to be particularly efficient compared with other actuation approaches, because it allows both high accuracy and high-bandwith operation as well as intrinsic capacitive measurement of displacement.…”

Fabrication and characterization of DRIE-micromachined electrostatic microactuators for hard disk drives

“…The comb drive actuator has thick silicon microstructures fabricated with deep micromachining, and the working plane of the actuator is perpendicular to the mounting plane of the suspension, which makes the actuator to have a typical 3-D structure. This creates a novel 3-D employment of comb drives that is different from the commonly planar arrangement of comb drive structures for HDD microactuators; including the planar linear and rotary comb drives (Imamura et al 1998;Horsley et al 1998;Tang 1990). It provides a large space in the actuator to arrange more comb drives so as to greatly enhance the driving force with a limited driving voltage, thus it can avoid the use of high voltage to drive the electrostatic devices.…”

“…Up to now, the most popular electrostatic microactuators are the lateral-driven linear actuators and rotary actuators, which were demonstrated by Fujitsu Ltd and IBM Corp., respectively (Imamura et al 1998;Horsley et al 1998). The linear electrostatic actuator was integrated with the head/slider, and the combined process is more cost-effective than the conventional slider fabrication process, but can be very complex and result in low production yield.…”